// SPDX-License-Identifier: GPL-2.0-only
/*
 * kernel/locking/mutex.c
 *
 * Mutexes: blocking mutual exclusion locks
 *
 * Started by Ingo Molnar:
 *
 *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *
 * Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and
 * David Howells for suggestions and improvements.
 *
 *  - Adaptive spinning for mutexes by Peter Zijlstra. (Ported to mainline
 *    from the -rt tree, where it was originally implemented for rtmutexes
 *    by Steven Rostedt, based on work by Gregory Haskins, Peter Morreale
 *    and Sven Dietrich.
 *
 * Also see Documentation/locking/mutex-design.rst.
 */
#include <generated/deconfig.h>
#include <linux/mutex.h>
#include <linux/ww_mutex.h>
#include <linux/sched/signal.h>
#include <linux/sched/rt.h>
#include <linux/sched/wake_q.h>
#include <linux/sched/debug.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/debug_locks.h>
#include <linux/osq_lock.h>

#ifdef CONFIG_DEBUG_MUTEXES
# include "mutex-debug.h"
#else
# include "mutex.h"
#endif

void
__mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
{
//	atomic_long_set(&lock->owner, 0);
//	spin_lock_init(&lock->wait_lock);
//	INIT_LIST_HEAD(&lock->wait_list);
//#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
//	osq_lock_init(&lock->osq);
//#endif

//	debug_mutex_init(lock, name, key);
}
EXPORT_SYMBOL(__mutex_init);

/*
 * @owner: contains: 'struct task_struct *' to the current lock owner,
 * NULL means not owned. Since task_struct pointers are aligned at
 * at least L1_CACHE_BYTES, we have low bits to store extra state.
 *
 * Bit0 indicates a non-empty waiter list; unlock must issue a wakeup.
 * Bit1 indicates unlock needs to hand the lock to the top-waiter
 * Bit2 indicates handoff has been done and we're waiting for pickup.
 */
#define MUTEX_FLAG_WAITERS	0x01
#define MUTEX_FLAG_HANDOFF	0x02
#define MUTEX_FLAG_PICKUP	0x04

#define MUTEX_FLAGS		0x07

/*
 * Internal helper function; C doesn't allow us to hide it :/
 *
 * DO NOT USE (outside of mutex code).
 */
static inline struct task_struct *__mutex_owner(struct mutex *lock)
{
	return (struct task_struct *)(atomic_long_read(&lock->owner) & ~MUTEX_FLAGS);
}

static inline struct task_struct *__owner_task(unsigned long owner)
{
	return (struct task_struct *)(owner & ~MUTEX_FLAGS);
}

bool mutex_is_locked(struct mutex *lock)
{
	return __mutex_owner(lock) != NULL;
}
EXPORT_SYMBOL(mutex_is_locked);
//
//__must_check enum mutex_trylock_recursive_enum
//mutex_trylock_recursive(struct mutex *lock)
//{
//	if (unlikely(__mutex_owner(lock) == current))
//		return MUTEX_TRYLOCK_RECURSIVE;
//
//	return mutex_trylock(lock);
//}
//EXPORT_SYMBOL(mutex_trylock_recursive);
//
//static inline unsigned long __owner_flags(unsigned long owner)
//{
//	return owner & MUTEX_FLAGS;
//}
//
///*
// * Trylock variant that retuns the owning task on failure.
// */
//static inline struct task_struct *__mutex_trylock_or_owner(struct mutex *lock)
//{
//	unsigned long owner, curr = (unsigned long)current;
//
//	owner = atomic_long_read(&lock->owner);
//	for (;;) { /* must loop, can race against a flag */
//		unsigned long old, flags = __owner_flags(owner);
//		unsigned long task = owner & ~MUTEX_FLAGS;
//
//		if (task) {
//			if (likely(task != curr))
//				break;
//
//			if (likely(!(flags & MUTEX_FLAG_PICKUP)))
//				break;
//
//			flags &= ~MUTEX_FLAG_PICKUP;
//		} else {
//#ifdef CONFIG_DEBUG_MUTEXES
//			DEBUG_LOCKS_WARN_ON(flags & MUTEX_FLAG_PICKUP);
//#endif
//		}
//
//		/*
//		 * We set the HANDOFF bit, we must make sure it doesn't live
//		 * past the point where we acquire it. This would be possible
//		 * if we (accidentally) set the bit on an unlocked mutex.
//		 */
//		flags &= ~MUTEX_FLAG_HANDOFF;
//
//		old = atomic_long_cmpxchg_acquire(&lock->owner, owner, curr | flags);
//		if (old == owner)
//			return NULL;
//
//		owner = old;
//	}
//
//	return __owner_task(owner);
//}
//
///*
// * Actual trylock that will work on any unlocked state.
// */
//static inline bool __mutex_trylock(struct mutex *lock)
//{
//	return !__mutex_trylock_or_owner(lock);
//}
//
//#ifndef CONFIG_DEBUG_LOCK_ALLOC
///*
// * Lockdep annotations are contained to the slow paths for simplicity.
// * There is nothing that would stop spreading the lockdep annotations outwards
// * except more code.
// */
//
///*
// * Optimistic trylock that only works in the uncontended case. Make sure to
// * follow with a __mutex_trylock() before failing.
// */
//static __always_inline bool __mutex_trylock_fast(struct mutex *lock)
//{
//	unsigned long curr = (unsigned long)current;
//	unsigned long zero = 0UL;
//
//	if (atomic_long_try_cmpxchg_acquire(&lock->owner, &zero, curr))
//		return true;
//
//	return false;
//}
//
//static __always_inline bool __mutex_unlock_fast(struct mutex *lock)
//{
//	unsigned long curr = (unsigned long)current;
//
//	if (atomic_long_cmpxchg_release(&lock->owner, curr, 0UL) == curr)
//		return true;
//
//	return false;
//}
//#endif
//
//static inline void __mutex_set_flag(struct mutex *lock, unsigned long flag)
//{
//	atomic_long_or(flag, &lock->owner);
//}
//
//static inline void __mutex_clear_flag(struct mutex *lock, unsigned long flag)
//{
//	atomic_long_andnot(flag, &lock->owner);
//}
//
//static inline bool __mutex_waiter_is_first(struct mutex *lock, struct mutex_waiter *waiter)
//{
//	return list_first_entry(&lock->wait_list, struct mutex_waiter, list) == waiter;
//}
//
///*
// * Add @waiter to a given location in the lock wait_list and set the
// * FLAG_WAITERS flag if it's the first waiter.
// */
//static void
//__mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
//		   struct list_head *list)
//{
//	debug_mutex_add_waiter(lock, waiter, current);
//
//	list_add_tail(&waiter->list, list);
//	if (__mutex_waiter_is_first(lock, waiter))
//		__mutex_set_flag(lock, MUTEX_FLAG_WAITERS);
//}
//
//static void
//__mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter)
//{
//	list_del(&waiter->list);
//	if (likely(list_empty(&lock->wait_list)))
//		__mutex_clear_flag(lock, MUTEX_FLAGS);
//
//	debug_mutex_remove_waiter(lock, waiter, current);
//}
//
///*
// * Give up ownership to a specific task, when @task = NULL, this is equivalent
// * to a regular unlock. Sets PICKUP on a handoff, clears HANDOF, preserves
// * WAITERS. Provides RELEASE semantics like a regular unlock, the
// * __mutex_trylock() provides a matching ACQUIRE semantics for the handoff.
// */
//static void __mutex_handoff(struct mutex *lock, struct task_struct *task)
//{
//	unsigned long owner = atomic_long_read(&lock->owner);
//
//	for (;;) {
//		unsigned long old, new;
//
//#ifdef CONFIG_DEBUG_MUTEXES
//		DEBUG_LOCKS_WARN_ON(__owner_task(owner) != current);
//		DEBUG_LOCKS_WARN_ON(owner & MUTEX_FLAG_PICKUP);
//#endif
//
//		new = (owner & MUTEX_FLAG_WAITERS);
//		new |= (unsigned long)task;
//		if (task)
//			new |= MUTEX_FLAG_PICKUP;
//
//		old = atomic_long_cmpxchg_release(&lock->owner, owner, new);
//		if (old == owner)
//			break;
//
//		owner = old;
//	}
//}
//
//#ifndef CONFIG_DEBUG_LOCK_ALLOC
///*
// * We split the mutex lock/unlock logic into separate fastpath and
// * slowpath functions, to reduce the register pressure on the fastpath.
// * We also put the fastpath first in the kernel image, to make sure the
// * branch is predicted by the CPU as default-untaken.
// */
//static void __sched __mutex_lock_slowpath(struct mutex *lock);

/**
 * mutex_lock - acquire the mutex
 * @lock: the mutex to be acquired
 *
 * Lock the mutex exclusively for this task. If the mutex is not
 * available right now, it will sleep until it can get it.
 *
 * The mutex must later on be released by the same task that
 * acquired it. Recursive locking is not allowed. The task
 * may not exit without first unlocking the mutex. Also, kernel
 * memory where the mutex resides must not be freed with
 * the mutex still locked. The mutex must first be initialized
 * (or statically defined) before it can be locked. memset()-ing
 * the mutex to 0 is not allowed.
 *
 * (The CONFIG_DEBUG_MUTEXES .config option turns on debugging
 * checks that will enforce the restrictions and will also do
 * deadlock debugging)
 *
 * This function is similar to (but not equivalent to) down().
 */
void __sched mutex_lock(struct mutex *lock)
{
//	might_sleep();

//	if (!__mutex_trylock_fast(lock))
//		__mutex_lock_slowpath(lock);
}
EXPORT_SYMBOL(mutex_lock);
//#endif

///*
// * Wait-Die:
// *   The newer transactions are killed when:
// *     It (the new transaction) makes a request for a lock being held
// *     by an older transaction.
// *
// * Wound-Wait:
// *   The newer transactions are wounded when:
// *     An older transaction makes a request for a lock being held by
// *     the newer transaction.
// */
//
///*
// * Associate the ww_mutex @ww with the context @ww_ctx under which we acquired
// * it.
// */
//static __always_inline void
//ww_mutex_lock_acquired(struct ww_mutex *ww, struct ww_acquire_ctx *ww_ctx)
//{
//#ifdef CONFIG_DEBUG_MUTEXES
//	/*
//	 * If this WARN_ON triggers, you used ww_mutex_lock to acquire,
//	 * but released with a normal mutex_unlock in this call.
//	 *
//	 * This should never happen, always use ww_mutex_unlock.
//	 */
//	DEBUG_LOCKS_WARN_ON(ww->ctx);
//
//	/*
//	 * Not quite done after calling ww_acquire_done() ?
//	 */
//	DEBUG_LOCKS_WARN_ON(ww_ctx->done_acquire);
//
//	if (ww_ctx->contending_lock) {
//		/*
//		 * After -EDEADLK you tried to
//		 * acquire a different ww_mutex? Bad!
//		 */
//		DEBUG_LOCKS_WARN_ON(ww_ctx->contending_lock != ww);
//
//		/*
//		 * You called ww_mutex_lock after receiving -EDEADLK,
//		 * but 'forgot' to unlock everything else first?
//		 */
//		DEBUG_LOCKS_WARN_ON(ww_ctx->acquired > 0);
//		ww_ctx->contending_lock = NULL;
//	}
//
//	/*
//	 * Naughty, using a different class will lead to undefined behavior!
//	 */
//	DEBUG_LOCKS_WARN_ON(ww_ctx->ww_class != ww->ww_class);
//#endif
//	ww_ctx->acquired++;
//	ww->ctx = ww_ctx;
//}
//
///*
// * Determine if context @a is 'after' context @b. IOW, @a is a younger
// * transaction than @b and depending on algorithm either needs to wait for
// * @b or die.
// */
//static inline bool __sched
//__ww_ctx_stamp_after(struct ww_acquire_ctx *a, struct ww_acquire_ctx *b)
//{
//
//	return (signed long)(a->stamp - b->stamp) > 0;
//}
//
///*
// * Wait-Die; wake a younger waiter context (when locks held) such that it can
// * die.
// *
// * Among waiters with context, only the first one can have other locks acquired
// * already (ctx->acquired > 0), because __ww_mutex_add_waiter() and
// * __ww_mutex_check_kill() wake any but the earliest context.
// */
//static bool __sched
//__ww_mutex_die(struct mutex *lock, struct mutex_waiter *waiter,
//	       struct ww_acquire_ctx *ww_ctx)
//{
//	if (!ww_ctx->is_wait_die)
//		return false;
//
//	if (waiter->ww_ctx->acquired > 0 &&
//			__ww_ctx_stamp_after(waiter->ww_ctx, ww_ctx)) {
//		debug_mutex_wake_waiter(lock, waiter);
//		wake_up_process(waiter->task);
//	}
//
//	return true;
//}
//
///*
// * Wound-Wait; wound a younger @hold_ctx if it holds the lock.
// *
// * Wound the lock holder if there are waiters with older transactions than
// * the lock holders. Even if multiple waiters may wound the lock holder,
// * it's sufficient that only one does.
// */
//static bool __ww_mutex_wound(struct mutex *lock,
//			     struct ww_acquire_ctx *ww_ctx,
//			     struct ww_acquire_ctx *hold_ctx)
//{
//	struct task_struct *owner = __mutex_owner(lock);
//
//	lockdep_assert_held(&lock->wait_lock);
//
//	/*
//	 * Possible through __ww_mutex_add_waiter() when we race with
//	 * ww_mutex_set_context_fastpath(). In that case we'll get here again
//	 * through __ww_mutex_check_waiters().
//	 */
//	if (!hold_ctx)
//		return false;
//
//	/*
//	 * Can have !owner because of __mutex_unlock_slowpath(), but if owner,
//	 * it cannot go away because we'll have FLAG_WAITERS set and hold
//	 * wait_lock.
//	 */
//	if (!owner)
//		return false;
//
//	if (ww_ctx->acquired > 0 && __ww_ctx_stamp_after(hold_ctx, ww_ctx)) {
//		hold_ctx->wounded = 1;
//
//		/*
//		 * wake_up_process() paired with set_current_state()
//		 * inserts sufficient barriers to make sure @owner either sees
//		 * it's wounded in __ww_mutex_check_kill() or has a
//		 * wakeup pending to re-read the wounded state.
//		 */
//		if (owner != current)
//			wake_up_process(owner);
//
//		return true;
//	}
//
//	return false;
//}
//
///*
// * We just acquired @lock under @ww_ctx, if there are later contexts waiting
// * behind us on the wait-list, check if they need to die, or wound us.
// *
// * See __ww_mutex_add_waiter() for the list-order construction; basically the
// * list is ordered by stamp, smallest (oldest) first.
// *
// * This relies on never mixing wait-die/wound-wait on the same wait-list;
// * which is currently ensured by that being a ww_class property.
// *
// * The current task must not be on the wait list.
// */
//static void __sched
//__ww_mutex_check_waiters(struct mutex *lock, struct ww_acquire_ctx *ww_ctx)
//{
//	struct mutex_waiter *cur;
//
//	lockdep_assert_held(&lock->wait_lock);
//
//	list_for_each_entry(cur, &lock->wait_list, list) {
//		if (!cur->ww_ctx)
//			continue;
//
//		if (__ww_mutex_die(lock, cur, ww_ctx) ||
//		    __ww_mutex_wound(lock, cur->ww_ctx, ww_ctx))
//			break;
//	}
//}
//
///*
// * After acquiring lock with fastpath, where we do not hold wait_lock, set ctx
// * and wake up any waiters so they can recheck.
// */
//static __always_inline void
//ww_mutex_set_context_fastpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
//{
//	ww_mutex_lock_acquired(lock, ctx);
//
//	/*
//	 * The lock->ctx update should be visible on all cores before
//	 * the WAITERS check is done, otherwise contended waiters might be
//	 * missed. The contended waiters will either see ww_ctx == NULL
//	 * and keep spinning, or it will acquire wait_lock, add itself
//	 * to waiter list and sleep.
//	 */
//	smp_mb(); /* See comments above and below. */
//
//	/*
//	 * [W] ww->ctx = ctx	    [W] MUTEX_FLAG_WAITERS
//	 *     MB		        MB
//	 * [R] MUTEX_FLAG_WAITERS   [R] ww->ctx
//	 *
//	 * The memory barrier above pairs with the memory barrier in
//	 * __ww_mutex_add_waiter() and makes sure we either observe ww->ctx
//	 * and/or !empty list.
//	 */
//	if (likely(!(atomic_long_read(&lock->base.owner) & MUTEX_FLAG_WAITERS)))
//		return;
//
//	/*
//	 * Uh oh, we raced in fastpath, check if any of the waiters need to
//	 * die or wound us.
//	 */
//	spin_lock(&lock->base.wait_lock);
//	__ww_mutex_check_waiters(&lock->base, ctx);
//	spin_unlock(&lock->base.wait_lock);
//}
//
//#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
//
//static inline
//bool ww_mutex_spin_on_owner(struct mutex *lock, struct ww_acquire_ctx *ww_ctx,
//			    struct mutex_waiter *waiter)
//{
//	struct ww_mutex *ww;
//
//	ww = container_of(lock, struct ww_mutex, base);
//
//	/*
//	 * If ww->ctx is set the contents are undefined, only
//	 * by acquiring wait_lock there is a guarantee that
//	 * they are not invalid when reading.
//	 *
//	 * As such, when deadlock detection needs to be
//	 * performed the optimistic spinning cannot be done.
//	 *
//	 * Check this in every inner iteration because we may
//	 * be racing against another thread's ww_mutex_lock.
//	 */
//	if (ww_ctx->acquired > 0 && READ_ONCE(ww->ctx))
//		return false;
//
//	/*
//	 * If we aren't on the wait list yet, cancel the spin
//	 * if there are waiters. We want  to avoid stealing the
//	 * lock from a waiter with an earlier stamp, since the
//	 * other thread may already own a lock that we also
//	 * need.
//	 */
//	if (!waiter && (atomic_long_read(&lock->owner) & MUTEX_FLAG_WAITERS))
//		return false;
//
//	/*
//	 * Similarly, stop spinning if we are no longer the
//	 * first waiter.
//	 */
//	if (waiter && !__mutex_waiter_is_first(lock, waiter))
//		return false;
//
//	return true;
//}
//
///*
// * Look out! "owner" is an entirely speculative pointer access and not
// * reliable.
// *
// * "noinline" so that this function shows up on perf profiles.
// */
//static noinline
//bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner,
//			 struct ww_acquire_ctx *ww_ctx, struct mutex_waiter *waiter)
//{
//	bool ret = true;
//
//	rcu_read_lock();
//	while (__mutex_owner(lock) == owner) {
//		/*
//		 * Ensure we emit the owner->on_cpu, dereference _after_
//		 * checking lock->owner still matches owner. If that fails,
//		 * owner might point to freed memory. If it still matches,
//		 * the rcu_read_lock() ensures the memory stays valid.
//		 */
//		barrier();
//
//		/*
//		 * Use vcpu_is_preempted to detect lock holder preemption issue.
//		 */
//		if (!owner->on_cpu || need_resched() ||
//				vcpu_is_preempted(task_cpu(owner))) {
//			ret = false;
//			break;
//		}
//
//		if (ww_ctx && !ww_mutex_spin_on_owner(lock, ww_ctx, waiter)) {
//			ret = false;
//			break;
//		}
//
//		cpu_relax();
//	}
//	rcu_read_unlock();
//
//	return ret;
//}
//
///*
// * Initial check for entering the mutex spinning loop
// */
//static inline int mutex_can_spin_on_owner(struct mutex *lock)
//{
//	struct task_struct *owner;
//	int retval = 1;
//
//	if (need_resched())
//		return 0;
//
//	rcu_read_lock();
//	owner = __mutex_owner(lock);
//
//	/*
//	 * As lock holder preemption issue, we both skip spinning if task is not
//	 * on cpu or its cpu is preempted
//	 */
//	if (owner)
//		retval = owner->on_cpu && !vcpu_is_preempted(task_cpu(owner));
//	rcu_read_unlock();
//
//	/*
//	 * If lock->owner is not set, the mutex has been released. Return true
//	 * such that we'll trylock in the spin path, which is a faster option
//	 * than the blocking slow path.
//	 */
//	return retval;
//}
//
///*
// * Optimistic spinning.
// *
// * We try to spin for acquisition when we find that the lock owner
// * is currently running on a (different) CPU and while we don't
// * need to reschedule. The rationale is that if the lock owner is
// * running, it is likely to release the lock soon.
// *
// * The mutex spinners are queued up using MCS lock so that only one
// * spinner can compete for the mutex. However, if mutex spinning isn't
// * going to happen, there is no point in going through the lock/unlock
// * overhead.
// *
// * Returns true when the lock was taken, otherwise false, indicating
// * that we need to jump to the slowpath and sleep.
// *
// * The waiter flag is set to true if the spinner is a waiter in the wait
// * queue. The waiter-spinner will spin on the lock directly and concurrently
// * with the spinner at the head of the OSQ, if present, until the owner is
// * changed to itself.
// */
//static __always_inline bool
//mutex_optimistic_spin(struct mutex *lock, struct ww_acquire_ctx *ww_ctx,
//		      struct mutex_waiter *waiter)
//{
//	if (!waiter) {
//		/*
//		 * The purpose of the mutex_can_spin_on_owner() function is
//		 * to eliminate the overhead of osq_lock() and osq_unlock()
//		 * in case spinning isn't possible. As a waiter-spinner
//		 * is not going to take OSQ lock anyway, there is no need
//		 * to call mutex_can_spin_on_owner().
//		 */
//		if (!mutex_can_spin_on_owner(lock))
//			goto fail;
//
//		/*
//		 * In order to avoid a stampede of mutex spinners trying to
//		 * acquire the mutex all at once, the spinners need to take a
//		 * MCS (queued) lock first before spinning on the owner field.
//		 */
//		if (!osq_lock(&lock->osq))
//			goto fail;
//	}
//
//	for (;;) {
//		struct task_struct *owner;
//
//		/* Try to acquire the mutex... */
//		owner = __mutex_trylock_or_owner(lock);
//		if (!owner)
//			break;
//
//		/*
//		 * There's an owner, wait for it to either
//		 * release the lock or go to sleep.
//		 */
//		if (!mutex_spin_on_owner(lock, owner, ww_ctx, waiter))
//			goto fail_unlock;
//
//		/*
//		 * The cpu_relax() call is a compiler barrier which forces
//		 * everything in this loop to be re-loaded. We don't need
//		 * memory barriers as we'll eventually observe the right
//		 * values at the cost of a few extra spins.
//		 */
//		cpu_relax();
//	}
//
//	if (!waiter)
//		osq_unlock(&lock->osq);
//
//	return true;
//
//
//fail_unlock:
//	if (!waiter)
//		osq_unlock(&lock->osq);
//
//fail:
//	/*
//	 * If we fell out of the spin path because of need_resched(),
//	 * reschedule now, before we try-lock the mutex. This avoids getting
//	 * scheduled out right after we obtained the mutex.
//	 */
//	if (need_resched()) {
//		/*
//		 * We _should_ have TASK_RUNNING here, but just in case
//		 * we do not, make it so, otherwise we might get stuck.
//		 */
//		__set_current_state(TASK_RUNNING);
//		schedule_preempt_disabled();
//	}
//
//	return false;
//}
//#else
//static __always_inline bool
//mutex_optimistic_spin(struct mutex *lock, struct ww_acquire_ctx *ww_ctx,
//		      struct mutex_waiter *waiter)
//{
//	return false;
//}
//#endif
//
//static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigned long ip);

/**
 * mutex_unlock - release the mutex
 * @lock: the mutex to be released
 *
 * Unlock a mutex that has been locked by this task previously.
 *
 * This function must not be used in interrupt context. Unlocking
 * of a not locked mutex is not allowed.
 *
 * This function is similar to (but not equivalent to) up().
 */
void __sched mutex_unlock(struct mutex *lock)
{
//#ifndef CONFIG_DEBUG_LOCK_ALLOC
//	if (__mutex_unlock_fast(lock))
//		return;
//#endif
//	__mutex_unlock_slowpath(lock, _RET_IP_);
}
EXPORT_SYMBOL(mutex_unlock);

///**
// * ww_mutex_unlock - release the w/w mutex
// * @lock: the mutex to be released
// *
// * Unlock a mutex that has been locked by this task previously with any of the
// * ww_mutex_lock* functions (with or without an acquire context). It is
// * forbidden to release the locks after releasing the acquire context.
// *
// * This function must not be used in interrupt context. Unlocking
// * of a unlocked mutex is not allowed.
// */
//void __sched ww_mutex_unlock(struct ww_mutex *lock)
//{
//	/*
//	 * The unlocking fastpath is the 0->1 transition from 'locked'
//	 * into 'unlocked' state:
//	 */
//	if (lock->ctx) {
//#ifdef CONFIG_DEBUG_MUTEXES
//		DEBUG_LOCKS_WARN_ON(!lock->ctx->acquired);
//#endif
//		if (lock->ctx->acquired > 0)
//			lock->ctx->acquired--;
//		lock->ctx = NULL;
//	}
//
//	mutex_unlock(&lock->base);
//}
//EXPORT_SYMBOL(ww_mutex_unlock);
//
//
//static __always_inline int __sched
//__ww_mutex_kill(struct mutex *lock, struct ww_acquire_ctx *ww_ctx)
//{
//	if (ww_ctx->acquired > 0) {
//#ifdef CONFIG_DEBUG_MUTEXES
//		struct ww_mutex *ww;
//
//		ww = container_of(lock, struct ww_mutex, base);
//		DEBUG_LOCKS_WARN_ON(ww_ctx->contending_lock);
//		ww_ctx->contending_lock = ww;
//#endif
//		return -EDEADLK;
//	}
//
//	return 0;
//}
//
//
///*
// * Check the wound condition for the current lock acquire.
// *
// * Wound-Wait: If we're wounded, kill ourself.
// *
// * Wait-Die: If we're trying to acquire a lock already held by an older
// *           context, kill ourselves.
// *
// * Since __ww_mutex_add_waiter() orders the wait-list on stamp, we only have to
// * look at waiters before us in the wait-list.
// */
//static inline int __sched
//__ww_mutex_check_kill(struct mutex *lock, struct mutex_waiter *waiter,
//		      struct ww_acquire_ctx *ctx)
//{
//	struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
//	struct ww_acquire_ctx *hold_ctx = READ_ONCE(ww->ctx);
//	struct mutex_waiter *cur;
//
//	if (ctx->acquired == 0)
//		return 0;
//
//	if (!ctx->is_wait_die) {
//		if (ctx->wounded)
//			return __ww_mutex_kill(lock, ctx);
//
//		return 0;
//	}
//
//	if (hold_ctx && __ww_ctx_stamp_after(ctx, hold_ctx))
//		return __ww_mutex_kill(lock, ctx);
//
//	/*
//	 * If there is a waiter in front of us that has a context, then its
//	 * stamp is earlier than ours and we must kill ourself.
//	 */
//	cur = waiter;
//	list_for_each_entry_continue_reverse(cur, &lock->wait_list, list) {
//		if (!cur->ww_ctx)
//			continue;
//
//		return __ww_mutex_kill(lock, ctx);
//	}
//
//	return 0;
//}
//
///*
// * Add @waiter to the wait-list, keep the wait-list ordered by stamp, smallest
// * first. Such that older contexts are preferred to acquire the lock over
// * younger contexts.
// *
// * Waiters without context are interspersed in FIFO order.
// *
// * Furthermore, for Wait-Die kill ourself immediately when possible (there are
// * older contexts already waiting) to avoid unnecessary waiting and for
// * Wound-Wait ensure we wound the owning context when it is younger.
// */
//static inline int __sched
//__ww_mutex_add_waiter(struct mutex_waiter *waiter,
//		      struct mutex *lock,
//		      struct ww_acquire_ctx *ww_ctx)
//{
//	struct mutex_waiter *cur;
//	struct list_head *pos;
//	bool is_wait_die;
//
//	if (!ww_ctx) {
//		__mutex_add_waiter(lock, waiter, &lock->wait_list);
//		return 0;
//	}
//
//	is_wait_die = ww_ctx->is_wait_die;
//
//	/*
//	 * Add the waiter before the first waiter with a higher stamp.
//	 * Waiters without a context are skipped to avoid starving
//	 * them. Wait-Die waiters may die here. Wound-Wait waiters
//	 * never die here, but they are sorted in stamp order and
//	 * may wound the lock holder.
//	 */
//	pos = &lock->wait_list;
//	list_for_each_entry_reverse(cur, &lock->wait_list, list) {
//		if (!cur->ww_ctx)
//			continue;
//
//		if (__ww_ctx_stamp_after(ww_ctx, cur->ww_ctx)) {
//			/*
//			 * Wait-Die: if we find an older context waiting, there
//			 * is no point in queueing behind it, as we'd have to
//			 * die the moment it would acquire the lock.
//			 */
//			if (is_wait_die) {
//				int ret = __ww_mutex_kill(lock, ww_ctx);
//
//				if (ret)
//					return ret;
//			}
//
//			break;
//		}
//
//		pos = &cur->list;
//
//		/* Wait-Die: ensure younger waiters die. */
//		__ww_mutex_die(lock, cur, ww_ctx);
//	}
//
//	__mutex_add_waiter(lock, waiter, pos);
//
//	/*
//	 * Wound-Wait: if we're blocking on a mutex owned by a younger context,
//	 * wound that such that we might proceed.
//	 */
//	if (!is_wait_die) {
//		struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
//
//		/*
//		 * See ww_mutex_set_context_fastpath(). Orders setting
//		 * MUTEX_FLAG_WAITERS vs the ww->ctx load,
//		 * such that either we or the fastpath will wound @ww->ctx.
//		 */
//		smp_mb();
//		__ww_mutex_wound(lock, ww_ctx, ww->ctx);
//	}
//
//	return 0;
//}
//
///*
// * Lock a mutex (possibly interruptible), slowpath:
// */
//static __always_inline int __sched
//__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
//		    struct lockdep_map *nest_lock, unsigned long ip,
//		    struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx)
//{
//	struct mutex_waiter waiter;
//	bool first = false;
//	struct ww_mutex *ww;
//	int ret;
//
//	if (!use_ww_ctx)
//		ww_ctx = NULL;
//
//	might_sleep();
//
//#ifdef CONFIG_DEBUG_MUTEXES
//	DEBUG_LOCKS_WARN_ON(lock->magic != lock);
//#endif
//
//	ww = container_of(lock, struct ww_mutex, base);
//	if (ww_ctx) {
//		if (unlikely(ww_ctx == READ_ONCE(ww->ctx)))
//			return -EALREADY;
//
//		/*
//		 * Reset the wounded flag after a kill. No other process can
//		 * race and wound us here since they can't have a valid owner
//		 * pointer if we don't have any locks held.
//		 */
//		if (ww_ctx->acquired == 0)
//			ww_ctx->wounded = 0;
//	}
//
//	preempt_disable();
//	mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
//
//	if (__mutex_trylock(lock) ||
//	    mutex_optimistic_spin(lock, ww_ctx, NULL)) {
//		/* got the lock, yay! */
//		lock_acquired(&lock->dep_map, ip);
//		if (ww_ctx)
//			ww_mutex_set_context_fastpath(ww, ww_ctx);
//		preempt_enable();
//		return 0;
//	}
//
//	spin_lock(&lock->wait_lock);
//	/*
//	 * After waiting to acquire the wait_lock, try again.
//	 */
//	if (__mutex_trylock(lock)) {
//		if (ww_ctx)
//			__ww_mutex_check_waiters(lock, ww_ctx);
//
//		goto skip_wait;
//	}
//
//	debug_mutex_lock_common(lock, &waiter);
//
//	lock_contended(&lock->dep_map, ip);
//
//	if (!use_ww_ctx) {
//		/* add waiting tasks to the end of the waitqueue (FIFO): */
//		__mutex_add_waiter(lock, &waiter, &lock->wait_list);
//
//
//#ifdef CONFIG_DEBUG_MUTEXES
//		waiter.ww_ctx = MUTEX_POISON_WW_CTX;
//#endif
//	} else {
//		/*
//		 * Add in stamp order, waking up waiters that must kill
//		 * themselves.
//		 */
//		ret = __ww_mutex_add_waiter(&waiter, lock, ww_ctx);
//		if (ret)
//			goto err_early_kill;
//
//		waiter.ww_ctx = ww_ctx;
//	}
//
//	waiter.task = current;
//
//	set_current_state(state);
//	for (;;) {
//		/*
//		 * Once we hold wait_lock, we're serialized against
//		 * mutex_unlock() handing the lock off to us, do a trylock
//		 * before testing the error conditions to make sure we pick up
//		 * the handoff.
//		 */
//		if (__mutex_trylock(lock))
//			goto acquired;
//
//		/*
//		 * Check for signals and kill conditions while holding
//		 * wait_lock. This ensures the lock cancellation is ordered
//		 * against mutex_unlock() and wake-ups do not go missing.
//		 */
//		if (signal_pending_state(state, current)) {
//			ret = -EINTR;
//			goto err;
//		}
//
//		if (ww_ctx) {
//			ret = __ww_mutex_check_kill(lock, &waiter, ww_ctx);
//			if (ret)
//				goto err;
//		}
//
//		spin_unlock(&lock->wait_lock);
//		schedule_preempt_disabled();
//
//		/*
//		 * ww_mutex needs to always recheck its position since its waiter
//		 * list is not FIFO ordered.
//		 */
//		if (ww_ctx || !first) {
//			first = __mutex_waiter_is_first(lock, &waiter);
//			if (first)
//				__mutex_set_flag(lock, MUTEX_FLAG_HANDOFF);
//		}
//
//		set_current_state(state);
//		/*
//		 * Here we order against unlock; we must either see it change
//		 * state back to RUNNING and fall through the next schedule(),
//		 * or we must see its unlock and acquire.
//		 */
//		if (__mutex_trylock(lock) ||
//		    (first && mutex_optimistic_spin(lock, ww_ctx, &waiter)))
//			break;
//
//		spin_lock(&lock->wait_lock);
//	}
//	spin_lock(&lock->wait_lock);
//acquired:
//	__set_current_state(TASK_RUNNING);
//
//	if (ww_ctx) {
//		/*
//		 * Wound-Wait; we stole the lock (!first_waiter), check the
//		 * waiters as anyone might want to wound us.
//		 */
//		if (!ww_ctx->is_wait_die &&
//		    !__mutex_waiter_is_first(lock, &waiter))
//			__ww_mutex_check_waiters(lock, ww_ctx);
//	}
//
//	__mutex_remove_waiter(lock, &waiter);
//
//	debug_mutex_free_waiter(&waiter);
//
//skip_wait:
//	/* got the lock - cleanup and rejoice! */
//	lock_acquired(&lock->dep_map, ip);
//
//	if (ww_ctx)
//		ww_mutex_lock_acquired(ww, ww_ctx);
//
//	spin_unlock(&lock->wait_lock);
//	preempt_enable();
//	return 0;
//
//err:
//	__set_current_state(TASK_RUNNING);
//	__mutex_remove_waiter(lock, &waiter);
//err_early_kill:
//	spin_unlock(&lock->wait_lock);
//	debug_mutex_free_waiter(&waiter);
//	mutex_release(&lock->dep_map, ip);
//	preempt_enable();
//	return ret;
//}
//
//static int __sched
//__mutex_lock(struct mutex *lock, long state, unsigned int subclass,
//	     struct lockdep_map *nest_lock, unsigned long ip)
//{
//	return __mutex_lock_common(lock, state, subclass, nest_lock, ip, NULL, false);
//}
//
//static int __sched
//__ww_mutex_lock(struct mutex *lock, long state, unsigned int subclass,
//		struct lockdep_map *nest_lock, unsigned long ip,
//		struct ww_acquire_ctx *ww_ctx)
//{
//	return __mutex_lock_common(lock, state, subclass, nest_lock, ip, ww_ctx, true);
//}
//
//#ifdef CONFIG_DEBUG_LOCK_ALLOC
//void __sched
//mutex_lock_nested(struct mutex *lock, unsigned int subclass)
//{
//	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
//}
//
//EXPORT_SYMBOL_GPL(mutex_lock_nested);
//
//void __sched
//_mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest)
//{
//	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_);
//}
//EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
//
//int __sched
//mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass)
//{
//	return __mutex_lock(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_);
//}
//EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
//
//int __sched
//mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass)
//{
//	return __mutex_lock(lock, TASK_INTERRUPTIBLE, subclass, NULL, _RET_IP_);
//}
//EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
//
//void __sched
//mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
//{
//	int token;
//
//	might_sleep();
//
//	token = io_schedule_prepare();
//	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
//			    subclass, NULL, _RET_IP_, NULL, 0);
//	io_schedule_finish(token);
//}
//EXPORT_SYMBOL_GPL(mutex_lock_io_nested);
//
//static inline int
//ww_mutex_deadlock_injection(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
//{
//#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
//	unsigned tmp;
//
//	if (ctx->deadlock_inject_countdown-- == 0) {
//		tmp = ctx->deadlock_inject_interval;
//		if (tmp > UINT_MAX/4)
//			tmp = UINT_MAX;
//		else
//			tmp = tmp*2 + tmp + tmp/2;
//
//		ctx->deadlock_inject_interval = tmp;
//		ctx->deadlock_inject_countdown = tmp;
//		ctx->contending_lock = lock;
//
//		ww_mutex_unlock(lock);
//
//		return -EDEADLK;
//	}
//#endif
//
//	return 0;
//}
//
//int __sched
//ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
//{
//	int ret;
//
//	might_sleep();
//	ret =  __ww_mutex_lock(&lock->base, TASK_UNINTERRUPTIBLE,
//			       0, ctx ? &ctx->dep_map : NULL, _RET_IP_,
//			       ctx);
//	if (!ret && ctx && ctx->acquired > 1)
//		return ww_mutex_deadlock_injection(lock, ctx);
//
//	return ret;
//}
//EXPORT_SYMBOL_GPL(ww_mutex_lock);
//
//int __sched
//ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
//{
//	int ret;
//
//	might_sleep();
//	ret = __ww_mutex_lock(&lock->base, TASK_INTERRUPTIBLE,
//			      0, ctx ? &ctx->dep_map : NULL, _RET_IP_,
//			      ctx);
//
//	if (!ret && ctx && ctx->acquired > 1)
//		return ww_mutex_deadlock_injection(lock, ctx);
//
//	return ret;
//}
//EXPORT_SYMBOL_GPL(ww_mutex_lock_interruptible);
//
//#endif
//
///*
// * Release the lock, slowpath:
// */
//static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigned long ip)
//{
//	struct task_struct *next = NULL;
//	DEFINE_WAKE_Q(wake_q);
//	unsigned long owner;
//
//	mutex_release(&lock->dep_map, ip);
//
//	/*
//	 * Release the lock before (potentially) taking the spinlock such that
//	 * other contenders can get on with things ASAP.
//	 *
//	 * Except when HANDOFF, in that case we must not clear the owner field,
//	 * but instead set it to the top waiter.
//	 */
//	owner = atomic_long_read(&lock->owner);
//	for (;;) {
//		unsigned long old;
//
//#ifdef CONFIG_DEBUG_MUTEXES
//		DEBUG_LOCKS_WARN_ON(__owner_task(owner) != current);
//		DEBUG_LOCKS_WARN_ON(owner & MUTEX_FLAG_PICKUP);
//#endif
//
//		if (owner & MUTEX_FLAG_HANDOFF)
//			break;
//
//		old = atomic_long_cmpxchg_release(&lock->owner, owner,
//						  __owner_flags(owner));
//		if (old == owner) {
//			if (owner & MUTEX_FLAG_WAITERS)
//				break;
//
//			return;
//		}
//
//		owner = old;
//	}
//
//	spin_lock(&lock->wait_lock);
//	debug_mutex_unlock(lock);
//	if (!list_empty(&lock->wait_list)) {
//		/* get the first entry from the wait-list: */
//		struct mutex_waiter *waiter =
//			list_first_entry(&lock->wait_list,
//					 struct mutex_waiter, list);
//
//		next = waiter->task;
//
//		debug_mutex_wake_waiter(lock, waiter);
//		wake_q_add(&wake_q, next);
//	}
//
//	if (owner & MUTEX_FLAG_HANDOFF)
//		__mutex_handoff(lock, next);
//
//	spin_unlock(&lock->wait_lock);
//
//	wake_up_q(&wake_q);
//}
//
//#ifndef CONFIG_DEBUG_LOCK_ALLOC
///*
// * Here come the less common (and hence less performance-critical) APIs:
// * mutex_lock_interruptible() and mutex_trylock().
// */
//static noinline int __sched
//__mutex_lock_killable_slowpath(struct mutex *lock);
//
//static noinline int __sched
//__mutex_lock_interruptible_slowpath(struct mutex *lock);

/**
 * mutex_lock_interruptible() - Acquire the mutex, interruptible by signals.
 * @lock: The mutex to be acquired.
 *
 * Lock the mutex like mutex_lock().  If a signal is delivered while the
 * process is sleeping, this function will return without acquiring the
 * mutex.
 *
 * Context: Process context.
 * Return: 0 if the lock was successfully acquired or %-EINTR if a
 * signal arrived.
 */
int __sched mutex_lock_interruptible(struct mutex *lock)
{
//	might_sleep();

//	if (__mutex_trylock_fast(lock))
//		return 0;

//	return __mutex_lock_interruptible_slowpath(lock);
    return 0;
}

EXPORT_SYMBOL(mutex_lock_interruptible);

///**
// * mutex_lock_killable() - Acquire the mutex, interruptible by fatal signals.
// * @lock: The mutex to be acquired.
// *
// * Lock the mutex like mutex_lock().  If a signal which will be fatal to
// * the current process is delivered while the process is sleeping, this
// * function will return without acquiring the mutex.
// *
// * Context: Process context.
// * Return: 0 if the lock was successfully acquired or %-EINTR if a
// * fatal signal arrived.
// */
//int __sched mutex_lock_killable(struct mutex *lock)
//{
//	might_sleep();
//
//	if (__mutex_trylock_fast(lock))
//		return 0;
//
//	return __mutex_lock_killable_slowpath(lock);
//}
//EXPORT_SYMBOL(mutex_lock_killable);
//
///**
// * mutex_lock_io() - Acquire the mutex and mark the process as waiting for I/O
// * @lock: The mutex to be acquired.
// *
// * Lock the mutex like mutex_lock().  While the task is waiting for this
// * mutex, it will be accounted as being in the IO wait state by the
// * scheduler.
// *
// * Context: Process context.
// */
//void __sched mutex_lock_io(struct mutex *lock)
//{
//	int token;
//
//	token = io_schedule_prepare();
//	mutex_lock(lock);
//	io_schedule_finish(token);
//}
//EXPORT_SYMBOL_GPL(mutex_lock_io);
//
//static noinline void __sched
//__mutex_lock_slowpath(struct mutex *lock)
//{
//	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
//}
//
//static noinline int __sched
//__mutex_lock_killable_slowpath(struct mutex *lock)
//{
//	return __mutex_lock(lock, TASK_KILLABLE, 0, NULL, _RET_IP_);
//}
//
//static noinline int __sched
//__mutex_lock_interruptible_slowpath(struct mutex *lock)
//{
//	return __mutex_lock(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_);
//}
//
//static noinline int __sched
//__ww_mutex_lock_slowpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
//{
//	return __ww_mutex_lock(&lock->base, TASK_UNINTERRUPTIBLE, 0, NULL,
//			       _RET_IP_, ctx);
//}
//
//static noinline int __sched
//__ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
//					    struct ww_acquire_ctx *ctx)
//{
//	return __ww_mutex_lock(&lock->base, TASK_INTERRUPTIBLE, 0, NULL,
//			       _RET_IP_, ctx);
//}
//
//#endif

/**
 * mutex_trylock - try to acquire the mutex, without waiting
 * @lock: the mutex to be acquired
 *
 * Try to acquire the mutex atomically. Returns 1 if the mutex
 * has been acquired successfully, and 0 on contention.
 *
 * NOTE: this function follows the spin_trylock() convention, so
 * it is negated from the down_trylock() return values! Be careful
 * about this when converting semaphore users to mutexes.
 *
 * This function must not be used in interrupt context. The
 * mutex must be released by the same task that acquired it.
 */
int __sched mutex_trylock(struct mutex *lock)
{
//	bool locked;

//#ifdef CONFIG_DEBUG_MUTEXES
//	DEBUG_LOCKS_WARN_ON(lock->magic != lock);
//#endif

//	locked = __mutex_trylock(lock);
//	if (locked)
//		mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);

//	return locked;
    return 0;
}
EXPORT_SYMBOL(mutex_trylock);

//#ifndef CONFIG_DEBUG_LOCK_ALLOC
//int __sched
//ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
//{
//	might_sleep();
//
//	if (__mutex_trylock_fast(&lock->base)) {
//		if (ctx)
//			ww_mutex_set_context_fastpath(lock, ctx);
//		return 0;
//	}
//
//	return __ww_mutex_lock_slowpath(lock, ctx);
//}
//EXPORT_SYMBOL(ww_mutex_lock);
//
//int __sched
//ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
//{
//	might_sleep();
//
//	if (__mutex_trylock_fast(&lock->base)) {
//		if (ctx)
//			ww_mutex_set_context_fastpath(lock, ctx);
//		return 0;
//	}
//
//	return __ww_mutex_lock_interruptible_slowpath(lock, ctx);
//}
//EXPORT_SYMBOL(ww_mutex_lock_interruptible);
//
//#endif
//
///**
// * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0
// * @cnt: the atomic which we are to dec
// * @lock: the mutex to return holding if we dec to 0
// *
// * return true and hold lock if we dec to 0, return false otherwise
// */
//int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock)
//{
//	/* dec if we can't possibly hit 0 */
//	if (atomic_add_unless(cnt, -1, 1))
//		return 0;
//	/* we might hit 0, so take the lock */
//	mutex_lock(lock);
//	if (!atomic_dec_and_test(cnt)) {
//		/* when we actually did the dec, we didn't hit 0 */
//		mutex_unlock(lock);
//		return 0;
//	}
//	/* we hit 0, and we hold the lock */
//	return 1;
//}
//EXPORT_SYMBOL(atomic_dec_and_mutex_lock);
